Politically, one of the biggest mistakes Trump made today was his treatment of the media.
He's been blacklisting them all week (literally left them stranded on a bus days ago), and straight up embarrassed them today. Today's event was billed as a press conference but he refused to take any questions and only wanted coverage of his hotel. he got it and they were pressed about it (they deleted the hotel footage in protest).
I've noticed that the criticism of the media's coverage is starting to get to them. many NYT reporters in particular are now recognizing the pass they've given him and are now being more critical of him. It's obvious the mainstream media thought that by going easy on Trump, he'd remain accessible (ratings/clicks) but that hasn't been the case. He hasn't held a press conference in almost 2 months and has largely stuck to just Fox news.
I think if coverage of the election becomes even a little more balanced, it'll be very bad for Trump